Major cadence? Assuming you mean Perfect (V -> I) then yes, that is the main use of the b6 in the major scale - acting as a b9 to a V(7) chord to strengthen the cadence. I can't think of, nor find, any other really strong uses for it, but it does lead to interesting harmonies I suppose, with a iv chord instead of an IV, and a bVIaug chord instead of a VI, to name a few.
I'd be interested to hear any other formal uses for it though, I don't really know that much about it to be honest.
Last edited by theknuckster at May 29, 2011,